ADCV3 Test 3 Memo PDF

ADCV3 TEST 3 MEMO QUESTION 1 a) Name and identify (brief description) the roof structure below.  Space frame; Fully three-dimensional two-way spanning space framework (square on square)  (3D truss) is a rigid, lightweight, truss-like structure constructed from interl...

ADCV3 TEST 3 MEMO QUESTION 1 a) Name and identify (brief description) the roof structure below.  Space frame; Fully three-dimensional two-way spanning space framework (square on square)  (3D truss) is a rigid, lightweight, truss-like structure constructed from interlocking struts in a geometric pattern. b) Name four advantages and two disadvantages of roof structure identified in (a). Advantages  Loads distributed more Disadvantages evenly  Deflections reduces  Expensive  Easy installations of services  Fixed geometry  Fixing details simplified  Appear complicated  Factory made  Complex  Modular  Assembled at ground level QUESTION 2 a) Name two characteristics of a ferrous metal.  Contain iron  Ferrous metals can include mild steel, carbon steel, stainless steel, cast iron and wrought iron.  These metals are primarily used for their tensile strength & durability, especially mild steel which is used in building construction  b) Name two characteristics of a non-ferrous metal.  Do not contain iron  Non-ferrous metals include aluminium, brass, copper, nickel, titanium, lead and zinc, as well as precious metals like gold & silver  While non-ferrous metals can provide strength, they are primarily used where their differences from ferrous metals can provide an advantage.  High corrosion resistance  Good thermal and electrical conductivity  Non-magnetic c) Select & specify any two ferrous metals, and select & specify any two non-ferrous metals from the list below. Stainless Steel, Copper, Carbon fibre, Mild steel, Zinc, Aluminium, Polycarbonate QUESTION 3 a) Name a popular weathering steel. Cor-Ten steel b) Briefly explain how this weathering steel achieve its corrosion resistance.  With weathering steels, rusting is initiated in the same way, but the alloying elements react with the environment to form and adherent, less porous rust layer.  With time, this rust layer becomes protective and reduces the corrosion rate. c) Describe one of the disadvantages of a weathering steel.  Staining occurs and can result in a dirty look.  Provision should be made to divert corrosion products from vulnerable surfaces.  Often the south facades of buildings experience long periods of wetness and do not favour the formation of a protective rust patina. d) List points that should be avoided when using weathering steel.  Contact with absorbent surfaces (concrete)  Prolonged wet conditions  Burial in soils  Contact with dissimilar metals – galvanized or electroplated nuts & bolts are not suitable  Aggressive/marine environments  Usage on South façades e) List considerations for the use of weathering steel.  Corrosion allowance must be considered for long life  Crevices & water/dirt traps should be avoided  Rust staining may occur on adjacent surfaces  Surface blasting may be necessary for even weathering results  Fasteners should be made of weathering steel  Drainage should be carefully planned so runoff is directed to areas where it will not cause staining QUESTION 4 a) Identify the following metal roofing types from (i-iv) i) Klip-Lok ii) IBR Sheeting iii) Corrugated sheeting iv) Brownbuilt roofing  b) Specify which of above metal roofing types uses the concealed method of fixing and name an advantage of this type of fixing.  Brownbuilt & Klip-Lok  Concealed fixing is when the sheeting is secured to a specialized bracket that does not get exposed to the outside environment  Allows for superior watertightness compared to traditional screw-fix roofs. c) Specify the minimum recommended roof slope for roof sheet profile type (i). 0º, 3º, 5º, 7º, 10º, 15º, 17.5º 3º but the notes say 1º d) Specify the minimum recommended roof slope for roof sheet profile type (iii). 0º, 3º, 5º, 7º, 10º, 15º, 17.5º  When over lapped - 15º Or  Not over lapped - 7º e) Specify two major advantages of roof type (iv) over roof type (iii).  Brownbuilt sheeting (iv) can have a much smaller pitch than corrugated sheeting (iii)  Brownbuilt sheeting (iv) does not get penetrated in the fixing process therefore creating less opportunities for leaks unlike corrugated sheeting (iii)  Brownbuilt sheeting (iv) can be shaped and curved whereas corrugated sheeting (iii) cannot Brownbuilt Klip-Lok Corrugated IBR Pitch Smaller – As low as As low as 1˚ Larger – 10˚ > 15m 5˚ < 20m & 1˚ & 7,5˚ < 15m 7,5˚ > 30m Fixing & leaks Concealed/not Concealed/not Penetrated ⸫ higher Penetrated ⸫ penetrated ⸫ less penetrated ⸫ less chance of leaks higher leaks leaks chance of leaks Shaped & Yes Yes No* No * curved  f) Select the approximate maximum purlin spacing of roof type (i). 1.0m, 1.3m, 1.5m, 1.8m, 2.5m, 3.0m g) Polycarbonate is much lighter and more robust than glass. Name another major advantage of polycarbonate compared to glass.  Polycarbonate sheeting blocks UV rays whereas glass does not QUESTION 5 a) Name any four advantages of the galvanizing process.  Durable & long-lasting  Tough  Rust-free  Less maintenance  Clean finish, ideal for clinical environments b) Name any two disadvantages of the galvanizing process.  Considerably more expensive than steel prices, esp in large-scale projects  Not very aesthetically pleasing  Zinc hydroxide (white rust) can from if exposed to moisture; must be treated immediately to prevent reversal of galvanized coating/compromising durability  Not able to be applied on site  Dimensions of parts are limited by zinc bath size c) Corrugated mild steel roofing have been hot dipped galvanized to a specification of Z600. Calculate the zinc thickness per in micron. Mass per unit area Thickness (µm) = 2х7 600 = 42.86 µm 2х7 QUESTION 6 a) Explain the term “bimetallic/galvanic corrosion”.  An electrochemical process when one metal (anodic metal – sacrificial metal) corrodes preferentially when it is in electrical contact with a dissimilar metal in the presence of an electrolyte. b) Give an example of bimetallic/galvanic corrosion that might be problematic.  Bimetallic corrosion between steel & brass  When the protective paint layer peels or cracks, steel is exposed to oxygen & water which initiates corrosion c) Name a method how bimetallic/galvanic corrosion can be prevented.  Avoid creation of cavities  Welded joints are preferably bolted  Avoid or seal lap joints  Provide drainage holes for water  Provide free air circulation around structure QUESTION 7 a) Name four advantages and one disadvantage of Stainless Steel. Advantages  Long term value  Low maintenance costs  Versatile uses  Aesthetic value Disadvantages  Can be very expensive  Difficult to clean  Susceptible to scratches & dents  b) The four most popular grades of Stainless Steel used in the building industry today is 316, 430, 2205 and 304. List these four Stainless Steel grades from most to least corrosion resistance. 1) Type - 304 3) Type - 430 2) Type - 316 4) Type - 2205 c) Specify which Stainless-Steel grades should be specified for the following applications: i) Outside balustrade at office building in Newton Park - 316 ii) Internal stair balustrade - 304 iii) Outside balustrade for restaurant at the beachfront (20m from the water’s edge) - 316 iv) Outside balustrade at office building in Summerstrand - 316 v) Outside balustrade for a double storey house in Bloemfontein 304 d) Name the most corrosion resistant Stainless-Steel grade used in the building industry Type – Duplex 2205 e) Briefly explain why Stainless Steel is corrosion resistant  Lower alloy grades resist corrosion in normal atmospheric and potable water environments,  while the more highly alloyed grades can resist corrosion in many acids and alkaline solutions, and some chloride bearing environments, properties which are widely in process plants QUESTION 8 – SPECIFY TRUE OR FALSE a) Frequent cleaning of Stainless Steel by heavy rain or manual washing prevents corrosion. True / False b) Use a vertical surface finish grain orientation of Stainless-Steel cladding to prevent early discolouration/corrosion. True / False c) Marks and scratches on Stainless Steel can be removed by using steel wool.  True / False d) Galvanized fasteners should be used to fasten stainless steel panels. True / False e) Accumulation of dirt can lead to premature corrosion of Stainless-Steel panels. True / False QUESTION 9 a) Define a “curtain wall system”. Outer covering of a building in which the outer walls are non-structural, but merely keep the weather out and the occupants in. b) Name the following curtain wall systems. (i) (ii) Stick system Unitized system c) Describe the installation process of curtain wall system (i). Anchors are fixed to the floors of the building, then the design panels are fixed onto them. QUESTION 10 a) Name the type of beam in the illustration below and explain the reasoning for the holes.  Cellular beam.  Make it easier to run servicing directly through beams  20-50% lighter and 50% stronger than original beam (centroidal axis)  Invariably produce a more efficient & economical solution than castellated beams due to their greater flexibility. b) Name two advantages of this type of beam compared to conventional steel I-beam. Advantages  Increases strength (beam depth) without adding weight  Cheaper than traditional I-beam of equivalent strength  Easy installation of services  Flexible dimensions  Aesthetics Disadvantages:  Corrosion can occur if beam treated (galvanized) before cutting & welding. QUESTION 11 Draw an annotated sketch of detail (b). parapet wall (brick)  flashing  roofing/roof structure  rafter/fixing  insulation OTHER ROOFING DETAILS